The field of the present disclosure relates generally to a system and method of operating a power generating system to control a peak junction temperature. More particularly, the present disclosure relates to photovoltaic (e.g., solar power) and wind (e.g., wind turbine) power generating systems, including a controller that limits the peak junction temperature.
Typically, in power generation systems, the power produced by the solar module and wind turbine is direct-current (DC) power which must be converted to alternating current (AC) for export to the power grid. Typically, converters include insulated gate bipolar transistors (IGBTs) or other power semiconductors. The semiconductors typically operate within a normal range of operating temperatures. IGBT junction temperatures are typically rated at either 125° C., 150° C., or 175° C. maximum depending upon the type of IGBT. The semiconductors have an upper limit junction temperature at which they may be reliably operated. Exceeding the upper limit junction temperature of the semiconductors may cause undesirable reductions in operating efficiency and/or failure of the semiconductors.
Temperature increases at the semiconductor junctions may be caused by a variety of factors. For example, air filters of cooling systems for the semiconductors may become dirty/clogged thereby reducing an amount of cooling medium available to cool the semiconductors. Other environmental factors, such as high outdoor temperatures, high altitude, humidity levels, sunlight and the like may also undesirably increase the operating temperature of the semiconductors. Operating factors such as high output power of the converter and transient power events may also increase the junction temperature of the semiconductors and the like. Combinations of such factors may be applied simultaneously, causing more rapid and sustained high junction temperatures.
Typically, when the junction temperature of the semiconductors in the converter reaches an upper limit, a circuit breaker may be utilized to trip (i.e., shut down) the converter to prevent a failure of the converter. Further, operating the converters at high temperatures may undesirably reduce the life of the converter. If the converter is shut down due to high junction temperatures, the converter may remain in an off state until the semiconductor junction temperatures have decreased to an acceptable level. Such shutting down of the converter is typically undesirable because it may reduce or eliminate the ability for the power generating system to supply electrical power.